Cold in Place Rock Crushing and Stabilization of Northern Low ...

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Berthelot, Gerbrandt, Safronetz, and Sparks. Page: 1560,000Construction Costs ($/Km)50,00040,00030,00020,00010,0000No Stab (control)20% Clay20% Clay15% Clay15% Clay10% Clay-2-3l CaCl10% Clay-1l CaCl10% Clay-2l CaCl3l CaCl10% Clay-3l CaCl2l CaCl1l CaCl SealNo Stab & SealNo Stab (control)2.5% DL10SLabor Equipment Gravel Stabilizer Misc.6.5% DL10S4.5% DL10S Seal2.5% SS1 SealSeal Coat6.5% SS1 Seal4.5% SS1 SealNo Stab (control)FIGURE 15 Highway 918-01 Test Section Construction Cost per Kilometer by Cost Type$60,000Construction Cost ($/Km)$50,000$40,000$30,000$20,000$10,000$13,684$18,759$24,448$34,002$35,497$38,403$43,790$52,017$0GravelGravel w/ SealClay StabilizedClay/CaCl ModifiedCaCl ModifiedCaCl Modified w/ SealAsphalt Emulsion StabilizedAsphalt Emulsion Stabilized w/ SealFIGURE 16 Mean Total Construction Cost per Kilometer Grouped by Test Section Type
Berthelot, Gerbrandt, Safronetz, and Sparks. Page: 165 POST CONSTRUCTION PERFORMANCEInspection of the Highway 918-01 test sections was performed immediately after construction and one yearafter construction. For comparative purposes, a control test section comprised of in-place rock crushing with a gravelwearingsurface coarse and no stabilizers added to the subgrade was constructed. After one year of performance, theclay modified test sections were determined to exhibit improved stability of the subgrade, assisted in maintainingmoisture after rainfalls, and assisted in retaining gravel into the wearing coarse. However, the clay modified test sectionsproduced increased traffic dust in dry weather conditions and became slippery in wet weather conditions when comparedto other test sections.Calcium chloride modified test sections were constructed at concentrations of one liter/m 2 , two liter/m 2 andthree liter/m 2 to a depth of 150 mm. To evaluate the relative influence that clay has on the retention and performance ofcalcium chloride modification, test sections with and without ten percent clay by dry weight of subgrade soil wereconstructed. It was determined that calcium chloride provided improved compaction properties of the sand subgrade,assisted in moisture retention within the grade, and assisted in embedding gravel into the wearing coarse. The calciumchloride modified test sections significantly reduced dust in dry weather conditions when compared to other test sections.Clay modification of the calcium chloride treated subgrade increased the amount and duration of moisture retention. Itwas concluded that with ten percent clay added to the subgrade, one liter/m 2 of calcium chloride provided the optimalbalance of moisture retention and stability. Calcium chloride concentrations of two liters/m 2 and three liters/m 2 with tenpercent clay resulted in surface ponding, potholes, rutting, and slippery driving surface after rainfalls. It was alsodetermined that the calcium chloride without clay was less sensitive to rainfall and only exhibited minor surface pondingand potholes after rainfall up to concentrations of three liters/m 2 .SS-1 and DL10 Special asphalt emulsion was used to stabilize test sections at respective concentrations of 2.5,4.5 and 6.5 percent by dry weight of soil to a design depth of 150 mm. SS-1 is a slow set anionic asphalt emulsion thatemploys medium residual penetration asphalt designed to increase the stability and strength of granular materials. DL10Special is an anionic soft pen residual asphalt emulsion designed to provide added stability, improved environmentaldurability and surface workability in hot weather.Based on the observations of the SS-1 and DL10 Special asphalt emulsion stabilized test sections immediatelyafter construction, the test sections with increasing concentrations of asphalt emulsion increased the sand subgradestability, provided a tighter surface wearing coarse and reduced dust as would be expected. It was found that the asphalt
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